Question: $ { \left[\begin{array}{r}{1} \\ {3} \\ {1}\end{array}\right]-\left[\begin{array}{r}{2} \\ {1} \\ {3}\end{array}\right] = {?} } $
To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{r}{1}-{2} \\ {3}-{1} \\ {1}-{3}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{r}{-1} \\ {2} \\ {-2}\end{array}\right]}$